"This guy's a candidate," he says. Up ahead, a gray Saturn is weaving slightly, the driver-side wheels just crossing the double yellow line. A drunk driver?

Officer Delis isn't taking any chances. Police across the Island have narrowed the mesh on their nets.

According to the latest statistics from Edgartown district court, arrests for drunk driving on the Vineyard have risen sharply in the last two years. In 2000, police arrested 244 people for operating a vehicle under the influence of alcohol or a controlled substance.

Compared to the previous four years, when OUI arrests averaged 185 a year, that's more than a 30 per cent increase. Through September of this year, arrest numbers have already reached the 230 mark.

But a spike in arrests does not necessarily mean the problem of drunk driving has gotten worse. West Tisbury police chief Beth Toomey said it's more likely a combination of factors - more people on the Island, more police on the beat and a growing commitment to enforcement.

"It takes cops to make the arrests," said Chief Toomey, who pointed to beefed-up ranks both in her department and in those across the Island.

And the police, especially the younger recruits, are aggressive in their pursuit of drunk drivers.

"Seventeen thousand people a year die in alcohol-related accidents in this country," said Oak Bluffs police Sgt. Erik Blake. "But we don't call it an accident. We call it a crash. It's a decision you made."

Chief Toomey puts it this way: "An everyday person can have their life forever changed from drunk driving. It's a lethal weapon, and we have an obligation to stay on top of that."

To the chief and other police, enforcement equals lives saved.

Still, despite efforts to educate the drinking public about the risks of driving drunk, at least one other statistic points to a disturbing development in the battle to keep drivers sober. Statewide, according to department of public health (DPH) behavior risk surveys, adults who reported drinking and driving rose from 1.9 per cent in 1997 to 3.1 per cent in 1999.

But what about the Vineyard? The public health survey results were not broken down by community, but Islanders don't have to look far for evidence of the problem. The court log published each week in the papers is packed with OUI cases, but they are mostly the victimless variety.

Not last August. The victim was a 25-year-old woman from Estonia, struck from behind by a pick-up truck as she walked home around midnight along New York avenue in Oak Bluffs. Charged with drunk driving and motor vehicle homicide was former Tisbury selectman A. Kirk Briggs. His blood alcohol level, according to police, was .14, well over the legal limit of .08.

"Everyone was so upset when the girl got killed, asking how could this happen?" said Chief Toomey.

But the shock expressed over that one incident doesn't tell the whole story of how Islanders view drunk driving. Police and social workers point to a lax attitude, much like the one school leaders and therapists described last year in the wake of concerns about teenage drug and alcohol use.

"Our kids are a total reflection of what the Island feels about drinking. There's a high tolerance here," said the chief. "I have parents here who want me to find a place for kids to drink. They feel I'm negligent for not doing that."

You can blame some of that on the Island mentality, said Tom Bennett, clinical director of Island Counseling at Martha's Vineyard Community Services.

"We come from a manic-depressive culture here. In the summer, it's party time," he said. "We're exposed to this, and it's quite a force."

Visitors can get swept up in the same scene. "People make decisions on vacation they wouldn't necessarily make at home," said Sergeant Blake.

Not surprisingly, in such a setting, there would be some resentment, a perception of over-policing, when it comes to enforcement of drunk driving laws.

"A lot of people on the Vineyard feel there's an incredible amount of scrutiny of their driving," said Dr. Jane Dreeben, director of substance abuse services at Island Counseling.

And according to figures released by the state health department, Islanders are being ordered to attend the 16-week driver alcohol education course at a rate more than twice the state average. In 2000, the rate was 3.5 court referrals per 1,000 residents on the Vineyard, compared to 1.3 referrals per 1,000 residents statewide.

From there on out, police rely on their academy training to look for signs of an intoxicated driver. "You get good at knowing," said Chief Toomey.

The various field sobriety tests are well known - reciting the alphabet, touching index finger to the tip of the nose, walking the imaginary line and standing on one leg.

But increasingly, police are relying on the horizontal gaze as a good indicator. "You ask them to focus on the tip of the pen, and then you move it to the side," said Officer Delis. "If you're not under the influence, your eyes follow smoothly. If not, at maximum deviation, your eye will just sit there and bounce. It's really wild to see."

These tests are critical. Drivers pulled over by police can refuse to take the breathalyzer test, leaving police with no medical evidence to prove a driver was legally drunk. If challenged in court, it means a cop's word against the defendant's.

"It's frustrating," said Officer Delis. "If people could see what we see, they'd know we're not making this up."

Frustration seems to permeate the issue of drunk driving, from the cops to the courts and the alcohol classes.

"I think driving under the influence continues to be an enormous problem here," said Ms. Dreeben. "It's easy for people to lose sight of the fact that it's a potentially lethal act."

And when it does turn deadly, when one of those arrests is more than just a trip to the county jail, the frustration is even greater.

"I've responded to serious and fatal accidents in which alcohol was involved," said Jeff Pratt, ambulance coordinator for the Tisbury police. "No matter how old the story is, the frustration and pain are the same. You never get over the feeling of waste."